Tilley was a native of Cleveland, Ohio. Her parents were both former Vaudeville dancers who were killed in an auto accident when she was an infant. After her parents' death, Tilley was raised by her aunt, Shirley Ann Hawk who lived in Detroit.

Tilley joined the Velvelettes after one of the original members of the group left in 1966. She left the group to replace original Vandellas member Rosalind Ashford in 1969. Although her picture was on the cover of Sugar 'n' Spice, released in February 1970, it is unlikely she sang on the album. The first song she recorded with the Vandellas was "Something", which appeared originally on the 1970 album Natural Resources. She sang on the chart hit "Bless You", "Your Loves Makes It All Worthwhile" and the album Black Magic before the group splintered altogether following a farewell tour in 1972. Tilley's highlights as a Vandellas member included performing at the Copacabana in New York City with Judy Garland and F. Lee Bailey in the audience.

Tilley also toured the UK with the group when "Forget Me Not" became a top ten hit in the UK in 1970. Other highlights include appearances she made with the group on various television programs including The Mike Douglas show and popular dance show, Soul Train.

Tilley retired from the music industry and got married in July 1972.[4] Tilley developed a brain tumor around 1979, and surgery was performed at a hospital in Las Vegas, Nevada in mid-1981. Tilley died after having a brain aneurysm on September 9, 1981 at the age of 35 or 36 (sources differ).[5] Tilley had no children, and was survived by her husband and grandmother.